The invention relates to a non-mechanical printer or copier wherein a toner image is developed in a developing stage and applied to a tape-shaped recording medium in a transfer station. A fixing station is also provided for fixing the image
Non-mechanical printers such as laser printers, for example, are universally known and have been successfully employed.
With the assistance of a laser or a magnetic recording means, a latent image is generally produced on a photoconductive drum or on a magneto-sensitive drum. This latent image is developed by applying toner in a developing station and then is transferred to a band-like recording carrier in the following transfer station. The image consisting of toner loosely situated on the recording carrier is fixed with the assistance of a melt-fixing means such as is known, for example, from German OS No. 27 17 260, incorporated herein by reference. The band-like recording medium is then deposited via an automatic paper stacker.
In addition to standard hot-melt fixing employed in copiers functioning according to the xerographic principal, it is also known in laser printers such as disclosed in German Letters Pat. No. 30 48 477, corresponding to U.S. Ser. No. 319,727 incorporated herein by reference, to employ fixing stations wherein the fixing of the toner mixture occurs via a fixing agent vapor.
Given the high printing output of laser printers on the order of about 100 pages per minute and above, the paper consumption plays a large part. For this reason, numerous attempts have been undertaken to design the laser printer such that the verso or backside of the paper web can also be printed.
This, however, involves great difficulties since an ironing effect which prevents repeated printing, for example, for verso printing, occurs in the printer due to the known hot-melt fixing.
A further problem in laser printers is multi-color printing. It is in fact known from U.S. Pat. No. 3,991,713, incorporated herein by reference, to dispose a plurality of developing stations having toner of different colors at the circumference of the photoconductive drum. This is true for copiers in general. The transfer of this teaching to a laser printer, however, fails due to the high printing speed resulting in a mixing of the individual toners with one another. The frequently required cleaning of the individual developing stations would constantly interrupt the printer operation.
The same reservations also apply to non-mechanical printers or copiers wherein a magneto-sensitive drum on which the latent image is generated by magnetization is employed instead of the photoconductive drum.